The present invention relates generally to control devices for grain bin stirring apparatuses having down augers carried upon a support member which rotates horizontally about the grain bin for arcuate movement thereabout of said augers. More particularly a control mechanism is disclosed which does not permit the arcuate movement to commence until a predetermined rate of revolution of an auger associated with said switch is reached and which also automatically terminates the arcuate movement whenever the structure to which the associated auger is journaled is, for any reason, tipped beyond a predetermined angle.
Typical of the type of grain bin stirring apparatuses with which the present invention functions, are those revealed in U.S. Pat. No. 3,584,842 to Sukup and U.S. Pat. No. 4,162,857 to Spurling. These patents are representative of two basic styles of down auger grain bin stirring apparatuses. The Sukup patent discloses an apparatus which includes a wheeled carriage which moves radially and reciprocally with respect to a circular grain bin, upon its horizontal support member, whereas, Spurling disclosed down augers which are journaled directly to the horizontal support member and therefore, only move in a circular fashion about the bin. In both of these apparatuses a motor separate from that or those which drive the down augers is responsible for the arcuate movement of the horizontal support member, and it is that motor which is controlled by the present invention. In an apparatus employing a single source of motive power for both down auger rotation and the horizontal support member arcuate movement, the concept of the present invention could be employed with the addition of a solenoid controlled release clutch for the drive responsible for the arcuate movement or in some other known manner.
While grain bin stirring apparatuses of various designs have proven their viability, they are commonly subject to breakdown relating to the operation of their down augers as a result of down auger motor failure, pulley belt failure, and overloading due to wet grain conditions. As the augers travel around the bin, there will be some unavoidable trailing of the lower portion of the auger. However, when the augers veer too far from the perpendicular, due to one or more of these conditions, the force required to move the horizontal support member around the bin becomes magnified, and the chances for structural failure are increased.
Typically, in these apparatuses the horizontal support member is supported at the periphery of a circular grain bin by an end wheel running on a peripheral track and at the center by chains or rods hanging from the roof of the bin and supporting a swivel joint. Excessive deflection from the vertical of the down augers will set up forces tending to move the horizontal support member past the center of the grain bin and thereby causing the end wheel to jump the track. Some of the various methods in the prior art of stopping the arcuate movement of the horizontal support member in the event of such breakdown include an electronic sensor on the two ends of the end wheel drive, a switch on the center support structure sensitive to the movement of the horizontal support member in an upward direction, a mercury switch on the horizontal support member itself, and an on-off sail switch which energizes the motor driving the end wheel as a result of the spinning action of each auger.
In grain bin stirring apparatuses of the type which this invention is concerned, less force to initiate the arcuate movement of the horizontal support member is required if the rotation of the down augers has first commenced. Furthermore, the higher the rate of revolution of the down augers before initiating the arcuate movement of the horizontal support member about the grain bin, the easier it will be for the motor driving them arcuately through the grain mass to overcome its resistance. As a result, there will be less wear and tear and longer life of the associated parts if the arcuate movement is automatically delayed until the auger rotation first reaches a predetermined rate.
Of the aforementioned control devices, the sail switch is the only one which bases control of the arcuate movement of the horizontal support member on a predetermined rate of revolution of the augers. However, this device is complex, having many moving parts which are easily subject to breakdown themselves. These parts include a spring operated switch, a circular cover plate to hold the switch in the down, off position when the auger is not revolving at a sufficient rate, and a plurality of steel balls attached to arms which are again pivotally attached to the auger shaft. Many of these parts are themselves subject to breakdown or failure due to accumulated grime and dust or bending.